VCOADSR

Description

Allen Strange – Electronic Music – Chapters 1-4 exercises

The 2nd edition of “Electronic Music: Systems, techniques and controls” by Allen Strange published in 1983 is considered by many to be the definitive text on modular synthesis.

The book covers the subject of making electronic music from the perspective of technique starting from the very ‘basic’ patch of a filter and amplifier to more complex patches and ideas as you progress through the book. I have found that the book warrants repeated readings periodically as I have learnt more and it still continues to provide new information that previously had either overlooked or determined in appropriate at the time.

One area of the book that I had overlooked until recently were the projects and exercises at the end of each chapter intended by the author to enhance the reader’s understanding of various techniques. It is these projects and exercises that this series of posts will focus on were I will perform and complete these from the 2nd edition of “Electronic Music: Systems, techniques and controls” by Allen Strange published in 1983 (ISBN-10: 0697036022).

Chapters 1 to 3 give an overview of what ‘electronic music’ might be and how we might define it, how by being able to describe a sonic event parametrically with respect to pitch, volume, timbre etc that description has to be transferred to the instrument which in itself is not fixed in design. The basic parameters of sound are reviewed and how these relate to the available electronic sound sources in the early 1980’s. In chapter 1 (page 4) Strange makes in interesting comment that most users/music producers today would considered far more blurred, “But it should be recalled that the purpose of this book is to teach the user to play the instrument. Not everyone in involved with electronic music is especially interested in composing. And I am quite sure that the more competent performers of electronic instruments there are, the happier the composers of electronic music will be.” Anyway onto the practical exercises.

Chapter 4 – Basic Signal Processing: Amplifiers and Filters

This chapter starts with the basics of subtractive synthesis looking at amplification, gain and low pass filtering – all the exercises at the end of chapter 4 use the “basic patch” as shown in figure 4.12 (see below).

“Study and discuss the examples in figure 4.13. Try them out on available instruments and observe whether the sonic result is as described. If you have access to an oscilloscope, invent some similar examples. Take these patches apart and listen to how the signal sounds as it comes out of each module. A convenient way to do this is to make the patch in figure 4.14. The unprocessed oscillator can be heard by turning up pot A on the mixer; the signal from the filter before it reaches the amp can be heard by turning up pot B, and the whole series of processes is available at pot C.”

“If possible set the oscillator to a sub-audio frequency (you may have to use a special sub-audio oscillator), using the same patch as in figure 4.12. You will hear a series of clicks or pops that occur at the frequency of the oscillator. How does the fc of the filter affect these pops?”

Observations/comments about the patch:

For both examples the oscillator was set to 2Hz and sending either the sawtooth or square wave through the low pass filter naturally had the effect of removing the high frequencies and as the filter closes also reducing the amplitude too. In terms of a practical use for this the sawtooth wave acted as a pretty reasonable kick drum.

4.3. “If you have the available instruments configure three or more of the “basic patches” with sub-audio oscillators. Vary the frequency of each rhythm and also vary its prominence with the filter and the amp. If there are not enough amps and filters substitute the patch shown in figure 4.15.”

4.4 “At what point in the above exercise does a rhythm become a pitch?”

Observations/comments about the patch:

For this exercise I combined exercises 4.3 and 4.4 into one – the crossover point of when does rhythm become sound and sound become rhythm seems dependent on where you initially start the exercise.

“Build some interesting drone chords. Then using the patch in figure 4.15 sweep the fc of a low pass filter around to highlight different spectral areas of the drones.”

Observations/comments about the patch:

In this exercise I sequenced a drone chord progression and then sequenced the filter cutoff for each oscillator. The sweeps were fast changes as opposed to slow gradual ones. Even though the notes within the chords remains constant during the repeating sequence the effect of the sequenced low pass filter modulation creates interesting melodic patterns just by carving out different frequencies of each oscillator over time.

“Try “colouring’ some timbres or chords with bits of filtered noise, as in figure 4.16. How much noise can be added until the sense of pitch is lost? This is called masking. Is there a relationship between the filter’s fc (filtering the noise) and the oscillator’s frequency when this masking threshold is reached?”

Observations/comments about the patch:

In this exercise rather than just add the white noise to a constant tone I decided to band pass filter the white noise to a narrower frequency bandwidth and then slowly introduce a melodic set of tones. As the melody increase in amplitude you can hear a clear repeating melody, I then slowly reduced the amplitude of the band limited white noise (strictly speaking no longer white noise). As this occurs a second melodic element is heard that previously was hidden by the noise due to the fact that the frequencies of these notes broader occurred in the same frequency band as the white noise. From the exercise description this effect is masking and it is quite an interesting audio technique to hide something using noise and then slowly revealing it.

“Keeping in mind the idea of input, structure and output, combine two or more of these exercises and make some music.”

Observations/comments about the patch:

For this exercise I combined previous exercises 4.2 through 4.7 using a sub-audio oscillator to create the simple kick rhythm, a drone passing through a low pass filter being slowly opened throughout the track and low pass filtered white noise that is periodically opened and closed. As the white noise is filtered less the drone oscillator becomes increasingly masked by the noise whilst the sub-audio kick sits in the background.